This review provides a synthesis of current progress in the development of linked biogeochemical and vegetation models with a particular focus on nitrogen to help inform participants of the workshop on nitrogen processes and dynamic modelling of Convention on Long-range Transboundary Air Pollution (LRTAP). The workshop was followed by the 6th meeting of the Joint Expert Group on Dynamic Modelling of the Working Group on Effects, held in Brighton, United Kingdom on 26-28th October 2005. An overview is provided of four model chains namely: FORSAFE-VEG; SMART2-SUMO-MOVE-NTM; MAGICGBMOVE and VSD-BERN. Three biogeochemical models with less focus on acidification have also been reviewed: MERLIN, PnET and CENTURY. Key processes represented in the biogeochemical and vegetation models are compared together with data requirements and driving variables. A comparison of the abiotic model outputs used to predict plant species occurrence highlights some similarities but also key differences in the importance placed on individual variables such as availability of other nutrients, salinity and management. This influences the suitability of the models for simulating particular habitats. Remaining uncertainties and gaps to be discussed at the workshop include: \ud • What is a good measure of plant-available N and how good are our surrogate measures such as soil C/N in the models? \ud • Do models need to include direct effects of nitrogen above-ground not moderated by soil processes? \ud • Is there is a need to separate nitrogen species (inorganic and organic) in both the biogeochemical and plant occurrence models? \ud • Do models focused on biodiversity require a higher level of complexity than those required for acidification and enrichment of soils and water? \ud • How do we include feedbacks between the vegetation and biogeochemical models and what limitations does this impose if they are not included? \ud • What limitations in future model applications arise from the fixed or incomplete carbon cycles in some of the models? \ud • What are the advantages (e.g. extending climate envelopes) and disadvantages (e.g. varying ecological niches) for sharing data and response functions between countries to develop species / community models? \ud • How do we acquire data for southern Europe? \ud • Do we need to ensure consistency of approach across Europe? \ud • Would it be valuable to compare models using one or several test sites, to help understand the implications of underlying differences and aid model development? \ud • Should we be linking to groups working on N effects in waters to develop integrated catchment/landscape scenarios?\ud \ud Conclusions from the workshop will be synthesised together with recommendations in a summary report to help facilitate the future development and applications of dynamic models to meet both national and international requirements, in particular the LRTAP Convention and its Working Group on Effects. \u
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